This is the new hand symbol/gesture now used by literal nazis, as a another way of doing the “Sieg Heil”, or “Hitler Salute”. Once again, this gesture was originally not associated with Nazism and instead had several meanings with relationships, sports games, etc; however, in recent times neo-nazis and other far-right nationalists have been adopting new ways of dog whistling their message, and have now distorted this finger gesture.
The man did a four fingers salute; no one realized the true meaning of what he did.